Antibodies and Complements - Quan

Question 1

What are the 4 important features of antibodies?

Answer 1

• bind a variety of antigenic structures
• Exquisite discrimination of similar antigens
• Bind antigen with great strength
• Recognize antigen in its native form.

Question 2

What is the Overall mission of antibodies?

Answer 2

Neutralize target antigen

Question 3

__________ is tagging microbial organism or infected cells for phagocytosis.

Answer 3

opsonization

Question 4

______ recruit complement system to destroy microbial organisms or infected cells.

Answer 4

Complement fixation

Question 5

__________ bind toxins in the blood and tissue to facilitate the removal of the toxins.

Answer 5

Direct neutralization

Question 6

What is the major Immunoglobulin (Ig) in serum? What does it do?

Answer 6

G (IgG) = 70-75%
Provides;
neonatal immunity 
plays role in immunological memory 
IgG represents the basic structure of all Ig's

Question 7

Describe IgD….

Answer 7

Less than 1% of circulating Ig’s
A major component of B cell surface Ig
Also called b-cell receptor

Question 8

Describe IgE….

Answer 8

• Very scarce in serum
• Found of the surface of basophils
• Important for killing large parasites
• Contributes to allergic reaction

Question 9

Describe IgA…

Answer 9

• Is seceted into the saliva
• The receptor for IgA transports IgA across mucosal epithelium
• IgA usually assembled as a Dimer.

Question 10

Describe IgM…

Answer 10

• Around 10% of total Ig’s
• A pentamer of basic Ig structure
• Can serve as a B cell receptor
• The first secreted Ab in the response to the initial antigenic challenge.

Question 11

_____ complement is the Central component

Answer 11

C3

Question 12

______ - ______ complements are the late complements.

Answer 12

C5-C9

Question 13

What is the Complement family?

Answer 13

30 serum molecules that make of 10% of serum proteins.

Question 14

What does the complement family do?

Answer 14

A major defense system of the body that contributes to:
Control of inflammation 
Chemotaxis
Clearance of immune complexes
cellular activation
antimicrobial defense

Question 15

_____________ are the active complements.

Answer 15

Fragments of the complement molecules.

Question 16

How does complement activation occur?

Answer 16

Active site of complement is “Unmasked” by proteolytic cleavage, resulting in the exposure of the active site.

Question 17

Many complement components are ________.

Answer 17

Proenzymes

Question 18

The 3 principle functions of the complement system are what?

Answer 18

1. Opsonization & cell activation
2. Chemotaxis = small fragments of comp. form a concentration gradient to stimulate movement of immune cells to infection site.
3. Lysis of target cells = Activation make (MAC) which inserts into lipid bilayer, makes holes an causes lysis.

Question 19

Activation of complement system leads to _________ which causes ________.

Answer 19

• Formation of MAC

- causes lysis of microbe

Question 20

What are classic pathway activators?

Answer 20

Antibody-antigen complexes containing IgM or lg.-3

Question 21

What are lectin pathway activators?

Answer 21

Terminal mannose groups

Question 22

What are alternative pathway activators?

Answer 22

Microbial cell walls

Question 23

Which pathway activators are found on microbial surface?

Answer 23

Lectin & Alternative

Question 24

Know the summary of early stage activation of the alternative pathway….9 steps.

Answer 24

Spontaneous cleavage of C3 generate C3a & C3b—>C3b in fluid deactivated by hydrolysis—>C3b covalently bonds to cell surface–>Self surface bound C3b binds to factor H–>C3bH deactivated by factor I—>C3b bound to the surface of microbes binds to factor B–>C3bB is cleaved by factor D to generate C3bBb—>C3bBb is the alternative pathway C3 convertase.
*C3bBb catalyze significant amount of C3 Cleavage.

Question 25

___ is the adapter for the Classic pathway.

Answer 25

C1

Question 26

During the selective engagement by the classical pathway, _________ do not engage C1

Answer 26

Free antibody

Question 27

During selective engagement by the classical pathway, tissue bound antibody activates C1 generating what?

Answer 27

C1qr2s2

Question 28

What are the 3 steps of the Classical pathway?

Answer 28

Activated C1 cleave c2 and c4 to form C4b2a—->C4b2a is the classical c3 Convertase——> C4b2q3b is the classical C5 convertase.

Question 29

_____ is required for the invitation of MAC.

Answer 29

C5b